1. Field of the Invention
The present invention relates to a solenoid-operated valve which makes it possible to improve the durability of a diaphragm by reducing the load applied to a root portion of the diaphragm for opening/closing a fluid passage.
2. Description of the Related Art
Solenoid-operated valves have been hitherto used, for example, for controlling the flow direction of the compressed air by supplying the compressed air to an actuator or discharging the compressed air to the atmospheric air. The solenoid-operated valve generally adopts the system in which a valve plug is operated by a solenoid (electromagnet).
As shown in FIG. 4, such a solenoid-operated valve concerning the conventional technique comprises a coil housing 4 which includes a fixed iron core 1, a coil 2, and a movable iron core (plunger) 3 arranged therein, and a valve body 8. The valve body 8 is arranged with a diaphragm 7 for opening/closing a valve seat 6 to make communication between a pair of fluid inlet/outlet ports 5a, 5b (see Japanese Laid-Open Patent Publication No. 3-61776).
The diaphragm 7 has a thick-walled section 7a seated on the valve seat 6, and a thin-walled section 7b formed integrally with the thick-walled section 7a. A peripheral edge of the thin-walled section 7b is secured to a recess 9 of the valve body 8.
In this arrangement, when the electric power is applied to the coil 2, the attracting force is generated. The movable iron core 3 is displaced by the attracting force, and thus the diaphragm 7 is operated.
However, in the conventional solenoid-operated valve described above, whenever the diaphragm 7 is displaced integrally with the movable iron core 3 by the magnetically exciting action exerted on the coil 2 or the non-exciting action, the excessive load is applied to the vicinity (root portion) of the peripheral edge secured to the recess 9 of the valve body 8. Therefore, the durability of the diaphragm 7 is extremely deteriorated.
Further, it is preferable to increase the response speed of the solenoid-operated valve by enhancing the attracting force of the coil 2 by increasing the magnetic flux density brought about by the coil 2.
A general object of the present invention is to provide a solenoid-operated valve which makes it possible to improve the durability of a diaphragm by smoothly operating the diaphragm by reducing the load applied to a root portion of the diaphragm for opening/closing a fluid passage.
A principal object of the present invention is to provide a solenoid-operated valve which makes it possible to increase the response speed by enhancing the attracting force of a coil to be exerted on a movable iron core.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.